CHARLOTTE, N.C. (AP) — Tourism officials in Charlotte have hired an outside group to measure the economic impact of the Democratic National Convention.

The Charlotte Regional Visitors Authority usually makes visitor spending projections for large events. But those estimates have been questioned, so officials have hired Tourism Economics of Pennsylvania to conduct the study.

The authority initially estimated the convention could generate $75 million in visitor spending.

Last week's convention attracted as many as 35,000 people to Charlotte, including 15,000 journalists and 6,000 delegates.

Some economists point out that political conventions are so big, they crowd out normal business. It was not immediately clear if the new study will include the impact of business lost as well as the spending in the area.